What should be the number in the following series? 3 6 4 7 5 8

6 is the next number

6, 9, 7, 10, 8, 11 etc.. you basically add 2, then subtract 3.

Since the sequence is actually two sequences wrapped up, it can be split into the two sequences.

The first, third and fifth numbers are part of sequence, let's say, X.

Sequence X goes as follows: 3, 4, 5...

The second, fourth and sixth numbers are part of sequence Y.

Sequence Y goes as follows: 6, 7, 8...

Therefore, since the next number is the seventh number, it is part of sequence X, and since sequence X is going up in ones, it is most definitely a

6

.

This would mean that the next number would be part of sequence Y, and would be a 9, and so on, alternating sequences every number.